The study showed that Sweden's health system performed better regarding death rates 30 days after a heart attack. For Sweden the rate is 7.6% and for the UK it is 10.5%.
"Our findings are a cause for concern. The uptake and use of new technologies and effective treatments recommended in guidelines has been far quicker in Sweden. This has contributed to large differences in the management and outcomes of patients," Prof Harry Hemingway, one of the lead researchers, told the BBC.
The Swedish system is even better than the American in the treatment of heart-attacks, according to Tomas Jernberg, who was responsible for the Swedish contribution to the study.